1. Field of the Invention
The present invention relates to an exposure apparatus for exposing a wafer so as to transfer a reticle pattern onto the wafer, a coating/developing apparatus for coating a resist on a wafer and developing the resist-coated wafer, a method of transferring a substrate (e.g., a reticle, a wafer), a method of producing a device, a semiconductor production factory, and a method of maintaining an exposure apparatus.
2. Description of the Related Art
A recent trend in the exposure apparatus industry has been to reduce the wavelength of exposure light to enhance resolution, thereby allowing exposure of an even finer pattern. A fluorine (F2) excimer laser is an example of a light source capable of emitting light with a short wavelength. If an exposure apparatus employs a fluorine excimer laser, however, it is necessary to purge oxygen (O2) from the optical path of the exposure light to prevent a reduction in transmission of the exposure light. More specifically, it is desirable that the oxygen concentration in the path of the exposure light be less than about 1 ppm.
When a substrate such as a wafer or a reticle is transferred from a coating/developing apparatus (CD apparatus), having an ambient of atmospheric air, into an exposure apparatus, having a low-oxygen-concentration ambient such as an inert gas, the transfer is effected through a load lock chamber (LL chamber) to prevent intrusion of oxygen from the atmospheric air into the exposure apparatus. More specifically, the wafer or the reticle first is transferred from the CD apparatus into the LL chamber, which initially is filled with atmospheric air. The atmospheric air in the LL chamber then is replaced with an inert gas. After that, the wafer or the reticle is transferred into the exposure apparatus having an ambient of the inert gas.
A problem with the foregoing process is that it takes a long time to replace the atmospheric air in the LL chamber with the inert gas. Thus, the wafer or the reticle must remain in the LL chamber until the atmospheric air has been replaced. This limits throughput.
The present invention provides a technique for suppressing intrusion or leakage of an ambient gas which can occur when a substrate is carried between apparatuses such as an exposure apparatus, a coating/developing apparatus, and a load lock chamber, thereby achieving an improvement in throughput and a reduction in operating cost.
According to one aspect of the present invention, there is provided an exposure apparatus comprising an enclosure having a controllable internal ambient; a gate valve through which a substrate is transferred into or out of the enclosure; and gas ejection means for ejecting a gas into a region in close proximity to the gate valve, and in a direction substantially perpendicular to the direction of movement of the substrate as it is transferred into or out of the enclosure, wherein a gas curtain is formed by the gas ejected by the gas ejection means, such that an opening of the gate valve is shielded by the gas curtain. A stage on which a substrate such as a wafer or a reticle is placed during an exposure process may be provided within the enclosure.
According to another aspect of the present invention, there is provided a coating/developing apparatus comprising a resist coating unit for coating a resist on a wafer and a developing unit for developing the wafer. The coating/developing apparatus further comprises an enclosure in which the resist coating unit and the developing unit are disposed, the enclosure having a controllable internal environment; a gate valve through which a substrate is transferred into or out of the enclosure; and gas ejection means for ejecting a gas into a region in close proximity to the gate valve, and in a direction substantially perpendicular to the direction of movement of the substrate as it is transferred into or out of the enclosure, wherein a gas curtain is formed by the gas ejected by the gas ejection means, such that an opening of the gate valve is shielded by the gas curtain.
Preferably, the gas is ejected in a direction substantially parallel to a face of the substrate so that the substrate does not disturb the flow of the gas curtain as it passes therethrough.
Although the ejected gas may have the same composition as that of the atmospheric air, it is desirable to employ a gas having the same composition as that of the ambient gas in each chamber. More specifically, a gas having the same composition as that of a purge gas used to purge oxygen or moisture may be employed. An example is a pure inert gas such as pure nitrogen gas or pure helium gas. Use of such a gas makes it possible to create a gas curtain without causing an increase in the oxygen concentration of the ambient of the apparatus in which the gas curtain is created.
A guide may be disposed near a gas ejection unit for the gas curtain and also at the opposite end of the gas curtain to regulate the flow of the gas. This prevents mixing between the gas of the gas curtain and the ambient gas. Thus it is possible to form the gas curtain using a low-cost gas such as atmospheric air (or a gas having a higher oxygen content than the ambient gas). Even when an inert gas is used for the gas curtain, use of the guide prevents turbulent flow from occurring in the gas curtain, further enhancing the sealing capability.
In the present invention, although the gas of the gas curtain may be ejected at a constant flow rate throughout the process, it is preferable that, in order to reduce operating costs, the gas curtain be created only when necessary or that the flow rate of the gas curtain be changed as required.
In a specific example, a concentration detection means (such as a sensor, or a F2 light transmission meter) is disposed to detect the concentration of oxygen or moisture in the internal ambient of an enclosure enclosing an exposure apparatus, a coating/developing apparatus, or a load lock chamber disposed between the exposure apparatus and the coating/developing apparatus. A means is disposed for turning on or off the gas curtain or continuously varying the flow rate of the gas curtain in accordance with the concentration detected by the concentration detection means.
In another specific example, a substrate detection means (such as a sensor, or means for detection by means of a sequence) is disposed to detect the presence or absence of a substrate in a region close to the gate valve, and a means is disposed for turning on or off the gas curtain or continuously varying the flow rate of the gas curtain, in response to the detection of the presence or absence of the substrate.
In the system according to the present invention, when the gate valve is opened to transfer a substrate, if a sensor detects that the substrate is being passed through the gate valve, a control signal is sent to the flow rate control means to increase the flow rate of the gas curtain, thereby preventing the intrusion of oxygen. When wafers are continuously transferred, the opening in the gate valve is sealed with the gas curtain. Otherwise, the gate valve closes when transferring is not performed for a while. This allows the gas of the gas curtain to be saved.
In the system according to the present invention described above, it is possible to transfer a wafer or a reticle into the exposure apparatus even when the environment outside the exposure apparatus includes a relatively high oxygen concentration. This reduces the time needed to replace the gas in the load lock chamber with an inert gas.
According to still another aspect of the present invention, there is provided a method of transferring a reticle or a wafer into or out of an exposure apparatus, the method comprising the steps of controlling an ambient in an enclosure; opening and closing a gate valve disposed in the enclosure; transferring the reticle or the wafer into or out of the enclosure through the gate valve; and ejecting a gas into a region in close proximity to the gate valve and in a direction substantially perpendicular to the direction of movement of the reticle or the wafer as it is transferred into or out of the enclosure, wherein a gas curtain is formed by the ejected gas, such that an opening of the gate valve is shielded by the gas curtain.
Preferably, the exposure apparatus according to the present invention further includes a display, a network interface, and a computer for executing a network software program, thereby allowing maintenance information for the exposure apparatus to be transmitted by means of data communication via a computer network. The network software program provides a user interface displayed on the display to access, via an external network, a maintenance database provided by a vendor of the exposure apparatus or by a user thereof, thereby obtaining information from the maintenance database.
According to another aspect of the present invention, there is provided a method of producing a semiconductor device, including the steps of installing, in a semiconductor production factory, a plurality of production apparatuses for performing various processes including an exposure; and producing a semiconductor device by means of a plurality of processes using the production apparatuses. The method may further include the steps of connecting the production apparatuses to each other via a local area network; and transmitting, by means of data communication, information about at least one of the production apparatuses between the local area network and an external network outside the semiconductor production factory. The method may further include the step of accessing a database provided by a vendor of the exposure apparatus or provided by a user via an external network to obtain maintenance information for the exposure apparatus or the step of performing data communication with another semiconductor production factory, thereby managing production.
According to another aspect of the present invention, there is provided a semiconductor production factory, including a plurality of production apparatuses for performing various processes, including the exposure apparatus of the present invention; a local area network for connecting the plurality of production apparatuses; and a gateway for connecting the local area network to an external network outside the factory, thereby making it possible to transmit information about at least one of the production apparatuses by means of data communication.
According to still another aspect of the present invention, there is provided a method of maintaining an exposure apparatus, including the steps of providing, by a vendor of or a user of the exposure apparatus, a maintenance database connected to an external network outside a semiconductor production factory; giving permission to access the maintenance database from the semiconductor production factory via the external network; and transmitting maintenance information stored in the maintenance database to the semiconductor production factory via the external network.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments.